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Abstract:

An active antenna transceiver system is disclosed. The active antenna
transceiver system comprises a bandpass filter adapted to filter first
telecommunication signals in a first frequency band, the first
telecommunication signals being transceived in a first antenna section,
an active transceiver arrangement adapted to transceive second
telecommunications signal in a second frequency band, an antenna
arrangement adapted to radiate and/or collect signal in both the first
and second frequency bands. A combining element is provided for combining
first telecommunications signal and second telecommunication signal into
a combined telecommunications signal to be fed into antenna arrangement
and the combining element being adapted for splitting the combined
telecommunications signal from the antenna arrangement into first
telecommunication signals and second telecommunications signals.

Claims:

1. An active antenna system comprising: a bandpass filter adapted to
filter first telecommunication signals in a first frequency band, an
active transceiver arrangement adapted to transceive second
telecommunications signals in a second frequency band, an antenna
arrangement adapted to radiate signals in both the first frequency band
and the second frequency band; and a combining element adapted for
combining the first telecommunications signal and the second
telecommunication signal into a combined telecommunications signal to be
fed into the antenna arrangement.

2. The system according to claim 1, wherein the antenna arrangement is
adapted to receive signals in both the first frequency band and the
second frequency band; and the combining element is further adapted for
splitting a received combined telecommunications signal from the antenna
arrangement into a receive signal of the first telecommunication signal
and a receive signal of the second telecommunications signals

3. The system according to claim 1, wherein the active transceiver
arrangement is located adjacent to the antenna arrangement.

4. The system according to claim 1, wherein the first telecommunication
signals are collected in a first antenna section coupled to the bandpass
filter, the first antenna section comprising a corporate feeder network
coupled between the band pass filter and a first transceiver

5. The system according to claim 1, wherein the combining element is
adapted for combining the first telecommunications signal and the second
telecommunication signal into a combined telecommunications signal in a
substantially lossless manner

6. The system according to claim 1, the combining element comprising at
least one of a circulator and a summing junction.

7. The system according to claim 1, wherein a connection length between
the bandpass filter and the combining element is chosen such that the
bandpass filter appears as an open circuit for the second
telecommunications signal.

8. The system according to claim 1, comprising a first shunt resistance
connected between the combining arrangement and the band pass filter.

9. The system according to claim 1, the active transceiver arrangement
comprising a duplexer adapted to filter the second telecommunication
signal, the duplexer being coupled to the combining arrangement.

10. The system according to claim 5, wherein a coupling length between
the duplexer and the combining element is chosen such that the duplexer
appears as a high impedance for the first telecommunications signal.

11. The system according to claim 5, comprising a second shunt resistance
connected between the combining arrangement and the duplexer.

12. The system according to claim 1, the antenna arrangement comprising a
coupler adapted to extract a feedback signal from the combined
telecommunication signal, and an antenna element adapted to radiate and
receive signals in both the first frequency band and the second frequency
band, the coupler being located between the combining element and said
antenna element.

13. The system according to claim 8, comprising a third shunt resistance
connected between the combining arrangement and the combiner.

14. A method for combining signals in an active antenna system,
comprising: receiving at a bandpass filter a first telecommunications
signal in a first frequency band; filtering the first telecommunications
signal; transceiving/emitting, by an active transceiver arrangement, a
second telecommunications signal in a second frequency band; combining
the first telecommunications signal and the second telecommunication
signal into a combined telecommunications signal; and feeding into the
antenna arrangement located adjacent to the active transceiver
arrangement, the combined telecommunications signal to be radiated from
the antenna arrangement.

15. The method according to claim 14, wherein the first telecommunication
signal is collected a first antenna section coupled to the bandpass
filter, the first antenna section comprising a corporate feeder network
coupled between the bandpass filter and a first transceiver for
processing the first telecommunication signal

16. The method according to claim 14, wherein the combining the first
telecommunications signal and the second telecommunication signal is
substantially lossless

17. The method according to claim 14, comprising extracting, a feedback
signal from the combined telecommunication signal.

18. A method for splitting signals in an active antenna system,
comprising: receiving, into an antenna arrangement, a combined
telecommunications signal; splitting the combined telecommunications
signal from the antenna arrangement into a first telecommunication signal
in a first frequency band, the first telecommunication signal to be fed
to a first antenna section and into a second telecommunications signals
in a second frequency band to be fed into an active transceiver
arrangement; filtering the first telecommunications signal; inputting,
the first telecommunication signals into a first antenna section; and
transceiving/processing, by the active transceiver arrangement located
adjacent to antenna arrangement, the second telecommunications signal.

19. A method according to claim 18, wherein the first telecommunication
signal is collected in the first antenna section coupled to the bandpass
filter, the first antenna section comprising a corporate feeder network
coupled between the bandpass filter and a first transceiver for
processing the first telecommunication signal

20. The method according to claim 18, wherein the combining of the first
telecommunications signal and the second telecommunication signal is
substantially lossless

21. A computer program product comprising a non-transitory
computer-usable medium having control logic stored therein for causing a
computer to manufacture an active antenna transceiver system comprising:
a bandpass filter adapted to filter first telecommunication signals in a
first frequency band, an active transceiver arrangement adapted to
transceive second telecommunications signals in a second frequency band,
an antenna arrangement adapted to radiate signals in both the first
frequency band and the second frequency band, and a combining element
adapted for combining the first telecommunications signal and the second
telecommunication signal into a combined telecommunications signal to be
fed into the antenna arrangement.

22. A computer program product comprising a non-transitory
computer-usable medium having control logic stored therein for causing a
transceiver to execute a method for combining signals in an active
antenna transceiver system, comprising: first computer readable code
means receiving at a bandpass filter a first telecommunications signal in
a first frequency band; second computer readable code means filtering the
first telecommunications signal; third computer readable code means for
transceiving/emitting, in active transceiver arrangement, second
telecommunications signal in a second frequency band; fourth computer
readable code means for combining the first telecommunications signal and
the second telecommunication signal into a combined telecommunications
signal; and fifth computer readable code means for feeding, into an
antenna arrangement located adjacent to the active transceiver
arrangement, the combined telecommunications signal to be radiated from
the antenna arrangement.

23. A computer program product comprising a non-transitory
computer-usable medium having control logic stored therein for causing a
transceiver to execute a method for combining signals in an active
antenna transceiver system, comprising: first computer readable code
means for receiving, into an antenna arrangement, a combined
telecommunications signal; second computer readable code means for
splitting the combined telecommunications signal from the antenna
arrangement into a first telecommunication signal in a first frequency
band, the first telecommunication signal to be fed to a first antenna
section and into a second telecommunications signals in a second
frequency band to be fed into an active transceiver arrangement; third
computer readable code means for filtering the first telecommunications
signal; fourth computer readable code means for inputting, the first
telecommunication signals into a first antenna section; and fifth
computer readable code means for transceiving/processing, by the active
transceiver arrangement located adjacent to antenna arrangement, the
second telecommunications signal.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is related to U.S. patent application Ser.
No. 12/973,160, entitled: ACTIVE ANTENNA FOR FILTERING RADIO SIGNAL IN
TWO FREQUENCY BANDS, filed Dec. 20, 2010. The entire disclosure of the
foregoing application is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The field of the invention relates to an active antenna transceiver
system, a combined single band active and broadband passive antenna
system, and to a method for combining signals from active antenna
transceiver system and a broadband passive antenna.

BACKGROUND OF THE INVENTION

[0003] The use of mobile communications networks has increased over the
last decade. Operators of the mobile communications networks have
increased the number of base stations in order to meet an increased
demand for service by users of the mobile communications networks. The
operators of the mobile communications network wish to reduce the running
costs of the base station. One option to do this is to implement a radio
system as an antenna-embedded radio forming an active antenna array. Many
of the components of the antenna-embedded radio may be implemented on one
or more chips.

[0004] Nowadays active antenna arrays are used in the field of mobile
communications systems in order to reduce power transmitted to a handset
of a customer and thereby increase the efficiency of the base station,
i.e. the radio station. The radio station typically comprises a plurality
of antenna elements, i.e. an antenna array adapted for transceiving a
payload signal. Typically the radio station comprises a plurality of
transmit paths and receive paths. Each of the transmit paths and receive
paths are terminated by one of the antenna elements. The plurality of the
antenna elements used in the radio station typically allows steering of a
beam transmitted by the antenna array. The steering of the beam includes
but is not limited to at least one of: detection of direction of arrival
(DOA), beam forming, down tilting and beam diversity. These techniques of
beam steering are well-known in the art.

[0005] The antenna array or active antenna system is typically mounted on
a mast or tower. The antenna is coupled to the base transceiver station
(BTS) by means of a fibre optics cable and a power cable. The base
transceiver station is coupled to a fixed line telecommunications network
operated by one or more operators.

[0006] Equipment at the base of the mast as well as the active antenna
system mounted on the mast is configured to transmit and receive within
well defined limits set by communication standards.

[0007] The code sharing and time division strategies as well as the beam
steering rely on the radio station and the antenna array to transmit and
receive within well defined limits set by communication standards. The
communications standards typically provide a plurality of channels or
frequency bands useable for an uplink communication from the handset to
the radio station as well as for a downlink communication from the radio
station to the handset.

[0008] For example, the communication standard "Global System for Mobile
Communications (GSM)" for mobile communications uses different
frequencies in different regions. In North America, GSM operates on the
primary mobile communication bands 850 MHz and 1900 MHz. In Europe,
Middle East and Asia most of the providers use 900 MHz and 1800 MHz
bands.

[0009] As technology evolves, the operators have expressed a desire for an
active antenna product which is able to utilise the existing base-station
investments, in addition to providing a new system/band. For example, in
the roll-out of long term evolution (LTE) at 700 MHz (US) or 800 MHz
(EU), the operators would like to deploy a single antenna at the masthead
which could transmit the existing 900 MHz (EU) or 850 MHz (US) GSM
signals, using equipment at the base of the mast, as well as providing
active antenna functionality for the new LTE installation.

[0010] One solution could be to use a dual-band or broadband passive
antenna, with two traditional base-stations at the foot of the tower. For
example, the dual-band or broadband passive antenna would be mounted on a
mast adjacent to a traditional base-station `hut` or equipment cabin.
This solution however would suffer various drawbacks. Having a dual band
or broadband passive antenna would not allow the two bands to have
independent downtilt angles. Both bands would need to share the same
downtilt and this would be sub-optimal for either one or both systems,
depending upon the tilt angle chosen.

[0011] It would be useful to combine existing RF signals, hereafter
referred to as passive signal, emanating from (or travelling to) a base
station or remote radio head at the bottom of a mast (for example) with
signals from a different band, directly generated (or received) within
the active electronics of an active antenna system.

SUMMARY OF THE INVENTION

[0012] An active antenna system according to the disclosure comprises a
bandpass filter adapted to filter first telecommunication signals in a
first frequency band, an active transceiver arrangement adapted to
transceive second telecommunications signals in a second frequency band,
an antenna arrangement adapted to radiate signals in both the first
frequency band and the second frequency band, and a combining element
adapted for combining the first telecommunications signal and the second
telecommunication signal into a combined telecommunications signal to be
fed into the antenna arrangement.

[0013] In an aspect of the disclosure, the antenna arrangement is adapted
to receive signals in both the first frequency band and the second
frequency band, and the combining element is further adapted for
splitting a received combined telecommunications signal from the antenna
arrangement into a receive signal of the first telecommunication signal
and a receive signal of the second telecommunications signals.

[0014] In yet another aspect of the disclosure, the active transceiver
arrangement is located adjacent to the antenna arrangement.

[0015] In an aspect of the disclosure, the first telecommunication signals
are collected in a first antenna section coupled to the bandpass filter,
the first antenna section comprising a corporate feeder network coupled
between the band pass filter and a first transceiver.

[0016] The combining element may be adapted for combining the first
telecommunications signal and the second telecommunication signal into a
combined telecommunications signal in a substantially lossless manner.

[0017] In one aspect of the disclosure, the combining element comprises at
least one of a circulator and a summing junction.

[0018] In yet another aspect of the disclosure, a connection length
between the bandpass filter and the combining element is chosen such that
the bandpass filter appears as an open circuit for the second
telecommunications signal.

[0019] In yet another aspect of the disclosure, a first shunt resistance
is connected between the combining arrangement and the band pass filter.

[0020] In a further aspect of the disclosure, the active transceiver
arrangement comprising a duplexer adapted to filter the second
telecommunication signal, the duplexer being coupled to the combining
arrangement.

[0021] In yet another aspect of the disclosure, a coupling length between
the duplexer and the combining element is chosen such that the duplexer
appears as a high impedance for the first telecommunications signal.

[0022] A second shunt resistance may be connected between the combining
arrangement and the duplexer.

[0023] In another aspect of the disclosure, the antenna arrangement
comprises a coupler adapted to extract a feedback signal from the
combined telecommunication signal, and an antenna element adapted to
radiate and receive signals in both the first frequency band and the
second frequency band, the coupler being located between the combining
element and said antenna element.

[0024] A third shunt resistance may also be connected between the
combining arrangement and the combiner.

[0025] The present disclosure also teaches a method for combining signals
in an active antenna system. The method for combining signals in an
active antenna system comprises: receiving at a bandpass filter a first
telecommunications signal in a first frequency band; filtering the first
telecommunications signal; transceiving/emitting, by an active
transceiver arrangement, a second telecommunications signal in a second
frequency band; combining the first telecommunications signal and the
second telecommunication signal into a combined telecommunications
signal; and feeding into the antenna arrangement located adjacent to the
active transceiver arrangement, the combined telecommunications signal to
be radiated from the antenna arrangement.

[0026] In one aspect of the disclosure, the first telecommunication signal
is collected a first antenna section coupled to the bandpass filter, the
first antenna section comprising a corporate feeder network coupled
between the bandpass filter and a first transceiver for processing the
first telecommunication signal.

[0027] In another aspect of the disclosure, the combining the first
telecommunications signal and the second telecommunication signal is
substantially lossless.

[0028] In yet another aspect of the disclosure, the method comprises
extracting, a feedback signal from the combined telecommunication signal.

[0029] The present disclosure further teaches a method for splitting
signals in an active antenna system. The method for splitting signals in
an active antenna system comprises: receiving, into an antenna
arrangement, a combined telecommunications signal; splitting the combined
telecommunications signal from the antenna arrangement into a first
telecommunication signal in a first frequency band, the first
telecommunication signal to be fed to a first antenna section and into a
second telecommunications signals in a second frequency band to be fed
into an active transceiver arrangement; filtering the first
telecommunications signal; inputting, the first telecommunication signals
into a first antenna section; transceiving/processing, by the active
transceiver arrangement located adjacent to antenna arrangement, the
second telecommunications signal.

[0030] In one aspect of the disclosure, the first telecommunication signal
is collected in the first antenna section coupled to the bandpass filter,
the first antenna section comprising a corporate feeder network coupled
between the bandpass filter and a first transceiver for processing the
first telecommunication signal.

[0031] In another aspect of the disclosure, the combining of the first
telecommunications signal and the second telecommunication signal is
substantially lossless.

[0032] The present disclosure teaches a computer program product
comprising a non-transitory computer-usable medium having control logic
stored therein for causing a computer to manufacture an active antenna
transceiver system comprising: a bandpass filter adapted to filter first
telecommunication signals in a first frequency band, an active
transceiver arrangement adapted to transceive second telecommunications
signals in a second frequency band, an antenna arrangement adapted to
radiate signals in both the first frequency band and the second frequency
band, and a combining element adapted for combining the first
telecommunications signal and the second telecommunication signal into a
combined telecommunications signal to be fed into the antenna
arrangement.

[0033] The present disclosure also teaches a computer program product
comprising a non-transitory computer-usable medium having control logic
stored therein for causing a transceiver to execute a method for
combining signals in an active antenna transceiver system, comprising:
first computer readable code means receiving at a bandpass filter a first
telecommunications signal in a first frequency band; second computer
readable code means filtering the first telecommunications signal; third
computer readable code means for transceiving/emitting, in active
transceiver arrangement, second telecommunications signal in a second
frequency band; fourth computer readable code means for combining the
first telecommunications signal and the second telecommunication signal
into a combined telecommunications signal; fifth computer readable code
means for feeding, into an antenna arrangement located adjacent to the
active transceiver arrangement, the combined telecommunications signal to
be radiated from the antenna arrangement.

[0034] The present disclosure also teaches a computer program product
comprising a non-transitory computer-usable medium having control logic
stored therein for causing a transceiver to execute a method for
combining signals in an active antenna transceiver system, comprising:
first computer readable code means for receiving, into an antenna
arrangement, a combined telecommunications signal; second computer
readable code means for splitting the combined telecommunications signal
from the antenna arrangement into a first telecommunication signal in a
first frequency band, the first telecommunication signal to be fed to a
first antenna section and into a second telecommunications signals in a
second frequency band to be fed into an active transceiver arrangement;
third computer readable code means for filtering the first
telecommunications signal; fourth computer readable code means for
inputting, the first telecommunication signals into a first antenna
section; and fifth computer readable code means for
transceiving/processing, by the active transceiver arrangement located
adjacent to antenna arrangement, the second telecommunications signal.

DESCRIPTION OF THE FIGURES

[0035]FIG. 1 shows a combined single band active and broadband passive
antenna system, comprising an active antenna transceiver system according
to one aspect of the disclosure,

[0036]FIG. 2 shows a combined single band active and broadband passive
antenna system comprising an active antenna transceiver system according
to yet another aspect of the disclosure

[0037]FIG. 3 shows a method for combining transmission signals of
different frequency bands in an active antenna transceiver system
according to an aspect of the disclosure,

[0038]FIG. 4 shows a method for combining receive signals of different
frequency bands in an active antenna transceiver system according to an
aspect of the disclosure

DETAILED DESCRIPTION OF THE INVENTION

[0039] The invention will now be described on the basis of the drawings.
It will be understood that the embodiments and aspects of the invention
described herein are only examples and do not limit the protective scope
of the claims in any way. The invention is defined by the claims and
their equivalents. It will be understood that features of one aspect or
embodiment of the invention can be combined with a feature of a different
aspect or aspects and/or embodiments of the invention.

[0040] The term "base transceiver station (BTS)" in the context of this
disclosure includes, but is not limited to, base stations, as known from
GSM networks, as well as a node B (known from UMTS/3G networks) or
enhanced node B, and similar units used in other mobile communication
networks.

[0041] The term "subscriber device" in the context of this disclosure is
intended to encompass all types of mobile stations and other devices
connected to the mobile communication network. Such subscriber devices
can be portable or stationary. For example wireless modules can be
incorporated into vending machines for the transceiving of data over the
mobile communication network. Such wireless modules are also considered
to be subscriber devices.

[0042]FIG. 1 shows a combined single band active and broadband passive
antenna system 1 according to one aspect of the disclosure.

[0043] The single band active and broadband passive antenna system 1
comprises two antenna sections: a first antenna section 2, hereafter
referred to as the passive antenna section 2, and a second antenna
section 3 hereafter referred to as the active antenna section 3.

[0044] The passive antenna section 2 is adapted to transmit and receive
telecommunications signals to and from a base transceiver station 11. The
passive antenna section 2 typically corresponds to existing
installations, comprising the base transceiver station 11, one or more
coaxial feeder cables, 5 & 6 and a corporate feed network 12.

[0045] The passive antenna section 2 may be designed to transmit
telecommunications signals on a first transmit band TB1 and to receive
telecommunications signal on a first receive band RB1, as defined by
telecommunication standards. The passive antenna section 2 as exemplified
in the present disclosure is designed to transceive GSM signals in the
band of 900 MHz in Europe. The first transmit band TB1 comprises
frequencies preferably between 925 MHz and 960 MHz. The first receive
band RB1 comprises frequencies preferably between 880 MHz and 915 MHz.
However these frequencies are not limiting of the invention and any other
telecommunication bands could be contemplated.

[0047] The active transceiver arrangement 3-1, . . . , 3-N is adapted to
generate signals on a second, different transmit band TB2 and to receive
signals on a second, different receive band RB2. For example, the active
transceiver arrangement 3-1, . . . , 3-N may be designed to transceive
LTE signals in the band of 800 MHz in Europe. The second transmit band
TB2 comprises frequencies preferably between 790 MHz and 821 MHz. The
second receive band RB2 comprises frequencies preferably between 832 MHz
and 862 MHz. However this is not limiting the invention and any other
telecommunication bands could be contemplated.

[0048] The antenna element arrangement 4-1, . . . , 4-N is adapted to
radiate signals in the first transmit band TB1 fed from the passive
antenna section 2 and signals in the second transmit band TB2 fed from
the active transceiver arrangement 3-1, . . . , 3-N. The antenna element
arrangement 4-1, . . . , 4-N is further adapted to collect signals in the
first receive band RB1 to be fed to the passive antenna section 2 and
signals in the second receive band RB2 to be fed to the active
transceiver arrangement 3-1, . . . , 3-N.

[0049] The present disclosure is described with single transmit and
receive bands. However, this is not limiting of the invention, and the
passive antenna section 2 and/or the active transceiver arrangement 3-1,
. . . , 3-N may be multiband systems, adapted to transceive signals
covering more than one telecommunication band according to the
telecommunications standards.

[0050] The passive antenna section 2 is connected to the base transceiver
station 11 by means of a coaxial feeder cable 5 and a coaxial feeder
cable 6. The coaxial feeder cable 5 is adapted to carry telecommunication
signals at radio frequencies to and from the base transceiver station 11.
The coaxial feeder cable 6 is adapted to carry telecommunication signals
at radio frequencies to the base transceiver station 11 only.

[0051] The passive antenna section 2 comprises transmit-receive paths
1000-1, . . . , 1000-N, and receive only paths 1001-1, . . . , 1001-N.
There are eight different transmit-receive paths 1000-1, . . . , 1000-N,
and eight different receive only paths 1001-1, . . . , 1001-N displayed
within FIG. 1. It will however be appreciated by the person skilled in
the art that the number of the transmit-receive paths 1000-1, . . . ,
1000-N, and the number of the receive only paths 1001-1, . . . , 1001-N,
can be changed and is not limiting of the invention.

[0052] The transmit-receive paths 1000-1, . . . , 1000-N are adapted to
carry transmit signals 2000-T1, . . . , 2000-TN and receive signals
2000-R1, . . . , 2000-RN between the antenna element arrangement 30 and
the base transceiver station 11. The receive only paths 1001-1, . . . ,
1001-N are adapted to carry receive signals 2000-R1', . . . , 2000-RN',
from the antenna element arrangement 30 to the base transceiver station.
The aim of the receive only paths 1001-1, . . . , 1001-N is to implement
a diversity reception method, as is well-known in the art. The diversity
reception method will not be described in detail in the present
disclosure.

[0053] Although the passive antenna section 2 is described with the
transmit-receive path 1000-1, . . . , 1000-N and the receive only path
1001-1, . . . , 1001-N for implementing a diversity reception method,
this is not limiting of the invention. Any other implementation could be
contemplated and the passive antenna section 10 could have
transmit-receive paths 1000-1, . . . , 1000-N only.

[0055] Each one of the transmit-receive paths 1000-1, 1000-N is terminated
by an output to the active antenna section 3. As seen in FIG. 1, each one
of the transmit-receive paths 1000-1, 1000-N is coupled to a bandpass
filter 10-1, . . . , 10-N. The bandpass filter 10-1, . . . , 10-N allows
passage of the signal at frequencies in both the receive and transmit
frequency bands TB1, RB1 of the passive antenna section 2. The bandpass
filter 10-1, . . . , 10-N is a broadband filter covering the whole
frequency band, including both transmission frequencies and reception
frequencies.

[0057] The combining element 20-1, . . . , 20-N of FIG. 1 comprises a
circulator 20-1, . . . , 20-N. As will be described with reference to
FIG. 2, the combining element 20-1, . . . , 20-N could be a summing
junction. The combining element 20-1, . . . , 20-N could be a hybrid, a
resistive or other form of matched combiner. However, such a combiner is
not optimal in terms of power loss.

[0059] A first resistance R1-1, . . . , R1-N is placed between the band
pass filter 10-1, . . . , 10-N and the circulator 20-1, . . . , 20-N and
operates as a shunt resistance to the common or ground connection of the
unit. The first resistance R1-1, . . . , R1-N is preferably of high
impedance, to ensure that the arbitrary reflection coefficient of the
bandpass filter 10-1, . . . , 10-N is converted to a simple, known value.

[0062] The second transmit signal 2002-T1, . . . , 2002-TN comprises
signals of frequencies in the second transmit frequency band TB2. The
second receive signal 2002-R1, . . . , 2002-RN comprises signals of
frequencies in the second receive frequency band RB2.

[0063] The active transceiver arrangement 3-1, . . . , 3-N is shown as a
single band antenna arrangement. However this is not limiting of the
invention and the active transceiver arrangement 3-1, . . . , 3-N could
as well be a multiband antenna arrangement.

[0067] A second resistance R2-1, . . . , R2-N is placed between the
duplexer 30-1, . . . , 30-N and the circulator 20-1, . . . , 20-N and
operates as a shunt resistance to the common or ground connection of the
unit. The resistance R2-1, . . . , R2-N is preferably of high impedance,
to ensure that the arbitrary reflection coefficient of the duplexer 30-1,
. . . , 30-N is converted to a simple, known value.

[0069] The antenna element 70-1, . . . , 70-N is adapted to radiate the
first transmit signal 2000-T1, . . . , 200-TN and the second transmit
signal 2002-T1, . . . , 2002-TN, and to receive the first receive signal
2000-R1, . . . , 2000-RN and the second receive signal 2002-R1, . . . ,
2002-RN. The antenna element 70-1, . . . , 70-N is well-known and will
not be described in detail in the present disclosure.

[0070] The coupler is located between the circulator 20-1, . . . , 20-N
and the antenna element 70-1, . . . , 70-N. The coupler 60-1, . . . ,
60-N is adapted to extract part of the first transmit signals 2000-T1,
2000-TN and the second transmit signals, 2002-T1, 2002-TN to fed as a
feedback signal to a predistortion unit 80-1, . . . , 80-N. The
predistortion unit 80-1, . . . , 80-N provides predistortion compensation
to the second transmit signals, 2002-T1, 2002-TN, as is well known in the
art. It should be noted that the coupler 60-1, . . . 60-N is located
downstream of the circulator 20-1, . . . , 20-N for the transmit signals
in order to take into account the effect of the circulator 20-1, . . . ,
20-N in the predistortion compensation. It should also be noted that the
first transmit signals 2000-T1, 2000-TN are filtered out using a suitable
filter (not shown) downstream of the coupler 60-1, . . . , 60-N; it is
not possible for the predistorter to predistort these signals as they are
generated in the BTS cabinet or an external remote radio head and not
within the active electronics of the active antenna system.

[0071]FIG. 2 shows a combined single band active and broadband passive
antenna system 1' according to another aspect of the disclosure. The
combined single band active and broadband passive antenna system 1' of
FIG. 2 differs from the combined single band active and broadband passive
antenna system 1 of FIG. 1 in that the combing element 20' is a summing
junction 200-1, . . . , 200-N instead of a circulator 20-1, . . . , 20-N.

[0073] The advantages of the present invention, as disclosed in FIGS. 1
and 2, will be better understood when examining the propagation of the
telecommunication signals in the system. The propagation of the signals
is described with reference to FIG. 1.

[0074] The first transmit signal 2000-T1, . . . , 2000-TN is fed through
the coaxial cable from the external base transceiver station or RRH into
the transmit path 1000-1. The first transmit signal 2000-T1, . . . ,
2000-TN is of a frequency of the first transmit frequency band TB1. The
first transmit signal 2000-T1, . . . , 2000-TN is distributed by the
corporate feed network and a portion of it is passed into the bandpass
filter 10-1, . . . , 10-N. As mentioned above, the bandpass filter 10-1,
. . . , 10-N is adapted to pass through signals in both the receive and
transmit frequency bands TB1, RB1 of the passive antenna section 2.

[0076] The first transmit signal 2000-T1, . . . , 2000-TN exits at a third
port 23-1, . . . , 23-N leading to the antenna element 70-1, . . . , 70-N
where the first transmit signal 2000-T1, 2000-TN is to be radiated.

[0077] The man skilled in the art will be understood that the first
transmit signal 2000-T1, 2000-TN can not exit at the second port 22-1, .
. . , 22-N of the circulator 20-1, . . . , 20-N. Port 22-1, . . . , 22-N
leads to the duplexer 30-1, . . . , 30-N, which is adapted to let signal
pass having the second transmit frequency band TB2 and the second receive
frequency band RB2. In other words, the duplexer 30-1, . . . , 30-N acts
as a stop band for the first transmit signal 2000-T1, . . . , 2000-TN.

[0078] It should be noted that a connection length L2-1, . . . , L2-N
between the circulator 20-1, . . . , 20-N and the duplexer 30-1, . . . ,
30-N on the active transceiver arrangement side should be kept very
short, to avoid parasitic reflections. The short connection length L2-1,
. . . , L2-N allows the first transmit signal 2000-T1, . . . , 2000-TN to
simply see the duplexer 30-1, . . . , 30-N as an open circuit. This
prevents the first transmit signal 2000-T from travelling from the
combining element 20-1, . . . , 20-N to the duplexer 30-1, . . . , 30-N,
being reflected on the duplexer 30-1, . . . , 30-N and travelling back to
the combining element 20-1, . . . , 20-N. In other words, the connection
length L2-1, . . . , L2-N is kept short to ensure that it displays few,
if any, of the properties of a transmission line.

[0080] It is noted that the second transmit signal 2002-T1, . . . ,
2002-TN will not exit at the first port 21-1, . . . , 21-N, where the
second transmit signal 2002-T1, . . . , 2002-TN will encounter a high
reflection coefficient, in the form of the bandpass filter 10-1, . . . ,
10-N.

[0081] It should be understood that the connection length L1-1, . . . ,
L1-N between the circulator 20-1, . . . , 20-N and the bandpass filter
10-1, . . . , 10-N on the passive antenna section side should be kept
very short, to avoid parasitic reflections. A very short connection
length L1-1, . . . , L1-N allows the second transmit signal 2002-T1, . .
. , 2002-TN to see the stop-band of the bandpass filter 10-1, . . . ,
10-N as an open circuit. This prevents the second transmit signal
2002-T1, . . . , 2002-TN from travelling from the circulator 20-1, . . .
, 20-N to the bandpass filter 10-1, . . . , 10-N, being reflected at the
bandpass filter 10 and travelling back to the circulator 20-1, . . . ,
20-N. In other words, the connection length L1-1, . . . , L1-N is kept
short to ensure that it also displays few, if any, of the properties of a
transmission line.

[0082] A very short signal length could be typically in the order of less
than a tenth of the wavelength of the signals in any of: the transmit
band TB1, the receive band RB1, the transmit band TB2 or the receive band
RB2, but this is not limiting of the invention.

[0086] The second receive signal 2002-R1, . . . , 2002-RN will pass
through the receive band portion of the duplexer 30-1, . . . , 30-N and
on to the active receiver circuits of the active transceiver arrangement
3-1, . . . , 3-N.

[0087] It should be noted again that the second receive signal 2002-81, .
. . , 2002-RN can not exit at the first port 21-1, . . . , 21-N of the
circulator 20-1, . . . , 20-N. Indeed, the second receive signal 2002-R1,
. . . , 2002-RN will see the stop band of the bandpass filter 10-1, . . .
, 10-N and consequently will not exit at that port. If the connection
line L1-1, . . . , L1-N is short enough, this path appears as an open
circuit for the second receive signal 2002-R1, . . . , 2002-RN.

[0088] The propagation of the signals has been described with reference to
FIG. 1. It should be understood that the same sequence of events takes
place in the system of FIG. 2, with the exception that the signals will
simply flow directly to the desired port of the summing junction, instead
of propagating around the circulator.

[0089]FIG. 3 shows a method for combining transmission signals of
different frequency bands in an active antenna transceiver system
according to an aspect of the disclosure.

[0090] At step S1, the first transmit signal 2000-T1, . . . , 2000-TN
generated at the passive antenna section 2 is passed into the bandpass
filter 10-1, . . . , 10-N. The bandpass filter 10-1, . . . , 10-N is
adapted to pass through telecommunications signals in both the receive
frequency band RB1 and the transmit frequency band TB1.

[0097] While various embodiments of the present invention have been
described above, it should be understood that they have been presented by
way of example, and not limitation. It will be apparent to persons
skilled in the relevant arts that various changes in form and detail can
be made therein without departing from the scope of the invention. In
addition to using hardware (e.g., within or coupled to a central
processing unit ("CPU"), micro processor, micro controller, digital
signal processor, processor core, system on chip ("SOC") or any other
device), implementations may also be embodied in software (e.g. computer
readable code, program code, and/or instructions disposed in any form,
such as source, object or machine language) disposed for example in a
computer useable (e.g. readable) medium configured to store the software.
Such software can enable, for example, the function, fabrication,
modelling, simulation, description and/or testing of the apparatus and
methods describe herein. For example, this can be accomplished through
the use of general program languages (e.g., C, C++), hardware description
languages (HDL) including Verilog HDL, VHDL, and so on, or other
available programs. Such software can be disposed in any known computer
useable medium such as semiconductor, magnetic disc, or optical disc
(e.g., CD-ROM, DVD-ROM, etc.). The software can also be disposed as a
computer data signal embodied in a computer useable (e.g. readable)
transmission medium (e.g., carrier wave or any other medium including
digital, optical, analogue-based medium). Embodiments of the present
invention may include methods of providing the apparatus described herein
by providing software describing the apparatus and subsequently
transmitting the software as a computer data signal over a communication
network including the internet and intranets.

[0098] It is understood that the apparatus and method described herein may
be included in a semiconductor intellectual property core, such as a
micro processor core (e.g., embodied in HDL) and transformed to hardware
in the production of integrated circuits. Additionally, the apparatus and
methods described herein may be embodied as a combination of hardware and
software. Thus, the present invention should not be limited by any of the
above-described exemplary embodiments, but should be defined only in
accordance with the following claims and their equivalents.